US President Joe Biden slipped and fell while awarding diplomas at the US Air Force Academy graduation ceremony in Colorado.

Mr. Biden, the nation’s oldest serving president at 80, caught being helped up and walked back to his seat unaided after the incident.

The president had been standing for approximately an hour and a half, shaking hands with each of the 921 graduating cadets.

The White House communications director said “he’s fine”.

“There was a sandbag on stage while he was shaking hands,” Ben LaBolt wrote on Twitter.

The event rounded up shortly after the incident.

The unperturbed Biden was spotted sprinting back to his motorcade, apparently unharmed a moment after.

He did not respond to questions about the episode before his departure.

Earlier, Biden reminded US Air Force Academy graduates that they would be facing a rapidly changing world, emphasizing the need of US support for its friends and allies, as well as continuous US help for Ukraine.

“The American people’s support for Ukraine will not waiver. We always stand up for democracies, always,” Biden said to applause.

Critics say the US President is too old to run for a second term.

Following a physical test in February, doctors deemed Biden healthy and fit for responsibilities, noting that the President does not consume alcohol or tobacco and exercises “at least” five times per week.

Last June, Biden slipped while dismounting his bicycle after snaring a foot in a toe clip, but he was unharmed.